Make OffscreenCanvas animation in sync with its placeholder canvas's parent frame rate

content/browser/renderer_host/offscreen_canvas_surface_impl.h

Index: content/browser/renderer_host/offscreen_canvas_surface_impl.h
diff --git a/content/browser/renderer_host/offscreen_canvas_surface_impl.h b/content/browser/renderer_host/offscreen_canvas_surface_impl.h
index 9a28a5c3f6ab41708b95c9d63639c875920acd45..61d9c2d3d838028fff97162276ce4972b9c5cfea 100644
--- a/content/browser/renderer_host/offscreen_canvas_surface_impl.h
+++ b/content/browser/renderer_host/offscreen_canvas_surface_impl.h
@@ -17,11 +17,13 @@ class CONTENT_EXPORT OffscreenCanvasSurfaceImpl
     : public blink::mojom::OffscreenCanvasSurface {
  public:
   OffscreenCanvasSurfaceImpl(
+      const cc::FrameSinkId& parent_frame_sink_id,
       const cc::FrameSinkId& frame_sink_id,
       blink::mojom::OffscreenCanvasSurfaceClientPtr client);
   ~OffscreenCanvasSurfaceImpl() override;
 
-  static void Create(const cc::FrameSinkId& frame_sink_id,
+  static void Create(const cc::FrameSinkId& parent_frame_sink_id,
+                     const cc::FrameSinkId& frame_sink_id,
                      blink::mojom::OffscreenCanvasSurfaceClientPtr client,
                      blink::mojom::OffscreenCanvasSurfaceRequest request);
 
@@ -33,6 +35,9 @@ class CONTENT_EXPORT OffscreenCanvasSurfaceImpl
   void Satisfy(const cc::SurfaceSequence& sequence) override;
 
   const cc::FrameSinkId& frame_sink_id() const { return frame_sink_id_; }
+  const cc::FrameSinkId& parent_frame_sink_id() const {
+    return parent_frame_sink_id_;
+  }
   const cc::LocalFrameId& current_local_frame_id() const {
     return current_local_frame_id_;
   }
@@ -42,8 +47,9 @@ class CONTENT_EXPORT OffscreenCanvasSurfaceImpl
   mojo::StrongBindingPtr<blink::mojom::OffscreenCanvasSurface> binding_;
 
   // Surface-related state
-  cc::FrameSinkId frame_sink_id_;
+  const cc::FrameSinkId frame_sink_id_;
   cc::LocalFrameId current_local_frame_id_;
+  const cc::FrameSinkId parent_frame_sink_id_;
 
   DISALLOW_COPY_AND_ASSIGN(OffscreenCanvasSurfaceImpl);
 };